1. Field of the Invention
The present invention relates to audio processing apparatuses, and more particularly relates to an audio processing apparatus capable of reducing noise in an input audio signal.
2. Description of the Related Art
In general, video cameras which capture images and record the images along with audio signals input from microphones are known.
Furthermore, as a technique of reducing noise which is generated in an audio signal due to, for example, wind, and which is sensed by microphones, a method for reducing low-pitched sounds in opposite phases of two-channel audio data is known (refer to Japanese Patent Laid-Open No. 4-270599 corresponding to U.S. Pat. No. 5,550,925). Moreover, a method for changing a range of frequency in which the low-pitched sounds in opposite phase are reduced in accordance with a wind noise level is known.
In most DVD (digital versatile disc) video systems, 5.1 channel surround audio is recorded as audio data. The 5.1 channel surround audio has a plurality of audio channels, including an audio channel used mainly for a low frequency.
In recent years, video cameras capable of recording such 5.1 channel surround audio signals have been proposed. Specifically, audio signals obtained using a plurality of omnidirectional microphones are subjected to matrix calculation to be converted into 5.1 channel audio signals and recorded.
In a case where the method disclosed in Japanese Patent Laid-Open No. 4-270599 is employed, when audio signals corresponding to a plurality of channels are subjected to wind noise reduction processing and are converted into 5.1 channel surround audio, low-frequency components of the wind noise which failed to be removed may be emphasized.
Since the wind noise mainly includes low frequencies, when low-frequency components of the wind noise which failed to be removed are included in the low-frequency channel included in the converted 5.1 channel surround audio, harsh sound may be recorded.